Nutlet micromorphology of selected species of Nepeta (Lamiaceae) in Iran

27 June 2019

Amirmohammadi , Fatemeh-Zahra; Azizi, Majid; Nemati, Hossein ; Memariani, Farshid; Murphu, Ryan

A descriptive and comprehensive morphological and micro-morphological study of the nutlets in 16 selected Iranian taxa of Nepeta (Lamiaceae) was conducted using scanning electron microscopy (SEM) to evaluate nutlets characteristics for systematic relationships. Differences in surface ornamentation, size, shape, and nutlets color were observed between the species. The studied taxa are categorized in two basic types based on surface ornamentation, non-sculptured (smooth-type), and sculptured nutlets. The non-sculptured nutlets type can be divided into four sub-types, including smooth, granulate, undulate-cellular, and reticulate. In the sculptured nutlets, three subtypes of tuberculate, tuberculate-cellular, and verrucate are recognized. The shape of nutlets are described as oblong, ovoid-oblong, oblong-linear, to elliptic-oblong and their size range are 1.2-2 mm in length and 0.5-2 mm in width. According to the micrographs, the areole form and location are defined as bi-lobed, straight, basal, sub-basal and lateral. In addition, nutlet features of some Iranian taxa of Nepeta are reported for the first time. Nutlet micromorphological characteristics such as surface ornamentation can be useful for classification and identification of the medicinal species of the genus Nepeta in Iran.